CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Community Contributions

[ImmersedBoundary] Immersed Boundary Method in OpenFOAM-3.1-ext

Register Blogs Members List Search Today's Posts Mark Forums Read

Like Tree25Likes

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   March 12, 2018, 13:44
Default load in more than 1 STL geometries for immersed boundary
  #81
New Member
 
MWu
Join Date: Nov 2013
Posts: 10
Rep Power: 8
gnoyeh525 is on a distinguished road
Quote:
Originally Posted by hjasak View Post
Hi Robert,

Thank you for looking into this. Can you please send me the files you have changed to review the bug fixes and merge them in.

I am looking into the best way to rewrite the parallel communications in the Immersed Boundary to make everything faster, but this is a bigger project so it will require real funding. The comms we have now are fine for a smaller number of processors, but as the decomposition increases, the code will become inefficient. I will speak to Zeljko to see what we should do; however, some significant funding is required to get this fixed.

Regarding the writing of U and other fields: at this point in the code, the data from the IB points is interpolated into the points of the STL surface. The algorithm I am using is a surface walk, which is linear if the STL is clean and does not protrude outside of the background mesh. Ideally, the resolution of the STL surface should be comparable with the resolution of the background mesh.

I assume you found a case where the surface walk algorithm fails, eg. if the STL is folded over or similarly broken.

Hrv

Dear Prof. Jasak

Is that possible to load in two or more STL geometries for immersed boundary ?
i.e. instead of 1 sphere, load in many spheres ... thanks as always
gnoyeh525 is offline   Reply With Quote

Old   March 12, 2018, 13:47
Default
  #82
Senior Member
 
Hrvoje Jasak
Join Date: Mar 2009
Location: London, England
Posts: 1,846
Rep Power: 28
hjasak will become famous soon enough
Hi,

The STL can be in as many pieces as you like. I did not test the setup with multiple independent immersed boundaries in separate patches, so there may be problems related to coding; if you hit any we need some further development to deal with this.

You would only need to have true multiple IB patches (as opposed to having many bits of disconnected STL in a single immersed boundary) if you wish to post process eg forces on each bit separately.

Hope this helps,

Hrvoje
__________________
Hrvoje Jasak
Providing commercial FOAM/OpenFOAM and CFD Consulting: http://wikki.co.uk
hjasak is offline   Reply With Quote

Old   May 27, 2018, 17:29
Default
  #83
Member
 
Ben 017
Join Date: Nov 2017
Posts: 70
Rep Power: 4
Ben UWIHANGANYE is on a distinguished road
Hello
May you help to plot drag and lift coefficient in movingcylinderinchannel tutorial/immersedboundary/foam-extent 4.0?

I have changed the controlDict like this but it is printing out Cd=0, Cl=0 and Cm=0 for all time steps. what could be the reason behind?.


functions
{
forces
{

type forceCoeffs;
functionObjectLibs ( "libforces.so" );
outputControl timeStep;
outputInterval 1;
patches
(
wall
);
pName p;
UName U;
rhoName rhoInf;
log true;
rhoInf 1;
CofR ( 0 0 0 );
liftDir (0 1 0);
dragDir ( 1 0 0 );
pitchAxis ( 0 0 0 );
magUInf 1;
lRef 1;
Aref 1;
}
}
Ben UWIHANGANYE is offline   Reply With Quote

Old   September 16, 2018, 20:06
Default
  #84
New Member
 
KAMBIZ
Join Date: Jul 2017
Posts: 1
Rep Power: 0
Nikrouz is on a distinguished road
Hello everybody ....


I'm new to Foam extend .... as mentioned in release note of foam-extend 4.0, there have been significant improvements in Immersed Boundary Solvers. Is it possible to consider the immersed body as an "elastic structure"? If yes, which tutorials is suitable to start simulation?


Thanks everybody.
Nikrouz is offline   Reply With Quote

Old   October 18, 2018, 09:56
Default
  #85
zjz
New Member
 
赵嘉祯
Join Date: Nov 2017
Posts: 6
Rep Power: 4
zjz is on a distinguished road
Quote:
Originally Posted by hjasak View Post
For the record: we will release the latest version of immersed boundary in foam-extend-3.2

Hrv
Dear Professor Jasak:
I have run the example of movingCylinderInChannelIco without change it in foam extend 4.0, but when i open it with paraview and run it, there is a fatal error "size of field refValue(96) is not the same size as the patch(0) on patch ibCylinder of field U in file"movingCylinerInChannelIco/0.2/U", what is the reason for this?

Thanks for your reply!
zjz is offline   Reply With Quote

Old   May 16, 2019, 12:29
Default
  #86
New Member
 
Join Date: Oct 2018
Posts: 9
Rep Power: 3
mosaferkarbala is on a distinguished road
Send a message via Skype™ to mosaferkarbala
Quote:
Originally Posted by Phil_ View Post
Dear all,

so foam-extend next release (release 3.2) is available and I ran a small test for the immersed boundary.

For the kEpsilon turbulence model it works like a charm, but with the kOmegaSST model it complains about "tauWall not set for IB patch ibChannel for field U". In the kEpsilon model tauWall is set by the immersedBoundaryEpsilonWallFunction. This wall function is replaced by immersedBoundaryOmegaWallFunction where tauWall is not defined.

Any ideas?

In the meantime I'll dig in a little more and try to find out what's going on.

Phil
hey
do u find where this error comes from! im stuck on same error, any help would be appreciated
--> FOAM FATAL ERROR:
[0] tauWall not set for IB patch hull for field U
[0]
[0] From function const vectorField& immersedBoundaryVelocityWallFunctionFvPatchVectorF ield::wallShearStress() const
[0] in file wallFunctions/immersedBoundaryVelocityWallFunctions/immersedBoundaryVelocityWallFunctionFvPatchVectorF ield.C at line 200.

thanks
mosaferkarbala is offline   Reply With Quote

Old   August 30, 2019, 08:40
Default
  #87
New Member
 
rubingqin
Join Date: Apr 2019
Posts: 6
Rep Power: 2
Ginjames is on a distinguished road
Quote:
Originally Posted by Ben UWIHANGANYE View Post
Hello
May you help to plot drag and lift coefficient in movingcylinderinchannel tutorial/immersedboundary/foam-extent 4.0?

I have changed the controlDict like this but it is printing out Cd=0, Cl=0 and Cm=0 for all time steps. what could be the reason behind?.


functions
{
forces
{

type forceCoeffs;
functionObjectLibs ( "libforces.so" );
outputControl timeStep;
outputInterval 1;
patches
(
wall
);
pName p;
UName U;
rhoName rhoInf;
log true;
rhoInf 1;
CofR ( 0 0 0 );
liftDir (0 1 0);
dragDir ( 1 0 0 );
pitchAxis ( 0 0 0 );
magUInf 1;
lRef 1;
Aref 1;
}
}
Have you solved this problem?I have a same one. please help me,thank you very much
Ginjames is offline   Reply With Quote

Old   August 30, 2019, 11:12
Default Immersedbounday
  #88
New Member
 
Join Date: Oct 2018
Posts: 9
Rep Power: 3
mosaferkarbala is on a distinguished road
Send a message via Skype™ to mosaferkarbala
As u know there is no physical body in mesh because its immersed. So the wall type should be immersed boundary wall
Look at immersedboundary tutorials u will find it
mosaferkarbala is offline   Reply With Quote

Old   September 1, 2019, 04:53
Default
  #89
New Member
 
rubingqin
Join Date: Apr 2019
Posts: 6
Rep Power: 2
Ginjames is on a distinguished road
I am so appreciated for your reply. But there is no tutorials in IBM of forcecoeffs. I'm still confused about the zero. Below is my controldict about force and forcecoeffs. The patch name is my immersed boundary. So what should I do?Looking forward to your help!
best wishes!

functions
(
forces
{
type immersedBoundaryForces;
functionObjectLibs ("libimmersedBoundaryForceFunctionObject.so");


outputControl timeStep;
outputInterval 1;
patches ( ibCylinder );

pName p;
UName U;
rhoName rhoInf;
rhoInf 1;

log true;
CofR ( 0 0 0 );

Aref 0.05;
Uref 1;
}

forces
{
type forceCoeffs;
functionObjectLibs ( "libforces.so" );
//functionObjectLibs ("libimmersedBoundaryForceFunctionObject.so");
outputControl timeStep;
outputInterval 1;
patches ( ibCylinder );
pName p;
UName U;
log true;
rhoName rhoInf;
rhoInf 1;
CofR ( 0 0 0 );
liftDir ( 0 1 0 );
dragDir ( 0 0 1 );
pitchAxis ( 0 0 0 );
magUInf 1;
lRef 2.83;
Aref 0.05;
}
Ginjames is offline   Reply With Quote

Old   September 1, 2019, 14:06
Default Immersed boundary forces
  #90
New Member
 
Join Date: Oct 2018
Posts: 9
Rep Power: 3
mosaferkarbala is on a distinguished road
Send a message via Skype™ to mosaferkarbala
The first one in enough in foam extend immesrd bounday . Force coeff not needed.
After run afolder will create by name forces and u will find force and moments components inside it
Best regards
mosaferkarbala is offline   Reply With Quote

Old   September 1, 2019, 21:50
Default
  #91
New Member
 
rubingqin
Join Date: Apr 2019
Posts: 6
Rep Power: 2
Ginjames is on a distinguished road
So the last question is that I want to get the force coefficient, such as drag of friction coefficient,to do some verification. What should I do?How to calculate? Is the force in the forcefille in N/m3 or whatelse? Best gratitudes for you. I have stumbled for a long time. thank you again.
Ginjames is offline   Reply With Quote

Old   September 2, 2019, 01:00
Default
  #92
New Member
 
Join Date: Oct 2018
Posts: 9
Rep Power: 3
mosaferkarbala is on a distinguished road
Send a message via Skype™ to mosaferkarbala
Quote:
Originally Posted by Ginjames View Post
So the last question is that I want to get the force coefficient, such as drag of friction coefficient,to do some verification. What should I do?How to calculate? Is the force in the forcefille in N/m3 or whatelse? Best gratitudes for you. I have stumbled for a long time. thank you again.
Hi dear brother
I also faced with that problem since the force coeffs always get zero since dosent sense the immersed body. The way i used computing drag using forces directly using drag coeff formula which is the force component in the motion direction and the surface
Best regards
mosaferkarbala is offline   Reply With Quote

Old   September 2, 2019, 22:20
Default
  #93
New Member
 
rubingqin
Join Date: Apr 2019
Posts: 6
Rep Power: 2
Ginjames is on a distinguished road
So what is the dimension in the force fields? I tried to calculate drag force coeffs,but can't agree with the literature. I think my formula is wrong. It’s a shame that I don't figure out the force file,is it in N/m3 or N/m or something else? How you calculate it?
Ginjames is offline   Reply With Quote

Old   September 2, 2019, 22:53
Default
  #94
New Member
 
Join Date: Oct 2018
Posts: 9
Rep Power: 3
mosaferkarbala is on a distinguished road
Send a message via Skype™ to mosaferkarbala
Quote:
Originally Posted by Ginjames View Post
So the last question is that I want to get the force coefficient, such as drag of friction coefficient,to do some verification. What should I do?How to calculate? Is the force in the forcefille in N/m3 or whatelse? Best gratitudes for you. I have stumbled for a long time. thank you again.
Quote:
Originally Posted by Ginjames View Post
So what is the dimension in the force fields? I tried to calculate drag force coeffs,but can't agree with the literature. I think my formula is wrong. Itís a shame that I don't figure out the force file,is it in N/m3 or N/m or something else? How you calculate it?
Dimentions as i know is 3 major dimentions xyz, forces are in N and for drag
Fd =Cd*Ar*rhoV^2(1/2)
Fd is force in flow direction which in my case was -x direction, rho is ur fluid property and Ar is reference area which is 1D image of 3d shape that its surface vector is in flow direction
Thats it
For me this work quite fine
Best regards
mosaferkarbala is offline   Reply With Quote

Old   September 3, 2019, 21:17
Default
  #95
New Member
 
rubingqin
Join Date: Apr 2019
Posts: 6
Rep Power: 2
Ginjames is on a distinguished road
Thank you brother. It’s very useful.
Ginjames is offline   Reply With Quote

Reply

Tags
immersed boundary method, openfoam-1.6-ext, openfoam-3.1-ext

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Radiation in semi-transparent media with surface-to-surface model? mpeppels CFX 11 August 22, 2019 08:30
implementation of the Immersed Boundary Method mi_cfd Main CFD Forum 19 April 24, 2019 02:24
sliding mesh problem in CFX Saima CFX 45 September 22, 2015 11:53
Wrong flow in ratating domain problem Sanyo CFX 17 August 15, 2015 07:20
[ImmersedBoundary] who has the paper about immersed boundary method in openfoam blueshit OpenFOAM Community Contributions 1 November 18, 2013 08:16


All times are GMT -4. The time now is 11:32.